Jacob Aall Ottesen Preus II (January 8, 1920, Saint Paul, Minnesota – August 13, 1994) was a Lutheran pastor, professor, author, and church president. He served as the eighth president of the Lutheran Church - Missouri Synod from 1969-1981. He was a major figure in the Seminex affair which resulted in a schism in the Missouri Synod.
Preus attended Luther Seminary in Minneapolis, Minnesota, graduating in 1945. He was ordained a pastor and served several congregations in Minnesota. He received a Ph.D. from the University of Minnesota in 1951.
In 1958, he moved to Concordia Theological Seminary, then in Springfield, Illinois. He became the president of the seminary in 1962.
In 1969, Preus was elected president of the Missouri Synod, upsetting the incumbent, Oliver Harms. Preus represented a theologically more conservative wing of the Missouri Synod, and his administration worked to reverse the policies of the more moderate administrations preceding his.
In 1973-74, a battle over teachings at the Missouri Synod's flagship seminary, Concordia Seminary in St. Louis, resulted in the suspension of the president of Concordia Seminary, John Tietjen, and a walkout of seminary professors and students commonly referred to as Seminex. This resulted in a schism in the Missouri Synod, with a small group leaving the synod to form the Association of Evangelical Lutheran Churches. The AELC served as a catalyst for the merger of the moderate and liberal Lutheran churches in the United States into the Evangelical Lutheran Church in America in 1988.
Preus was named President Emeritus of the Missouri Synod in 1992.
Preus was known as a scholar of the Orthodoxy period of Lutheran history, especially of Lutheran theologian Martin Chemnitz. He translated many of Chemnitz's works into English, and wrote a biography of Chemnitz, The Second Martin: The Life and Theology of Martin Chemnitz.
Preus' father, J. A. O. Preus, was a politician who served as Minnesota's eighth state auditor and 20th governor. His brother, Robert Preus, was a professor at Concordia Seminary and later president of Concordia Theological Seminary. His son, J. A. O. Preus III, was a professor at Concordia Seminary and is the past president of Concordia University in Irvine, California.